Thermoplasmonic TiN boosts photocatalysis in covalent-organic frameworks

Abstract

Covalent-organic frameworks (COFs) hold promise for photocatalysis, but their efficiency is hindered by strong excitonic effects that limit charge separation and transfer. Here, we demonstrate a novel strategy to overcome this challenge by integrating thermoplasmonic TiN nanoparticles with a β-ketoenamine-linked COFs (TFP-BD). The enhanced local electromagnetic field generated by TiN promotes the separation of electron-hole pairs in TFP-BD. This enhancement is evidenced by a doubled carrier lifetime (∼0.99 ns) and photocurrent density (1.67 μA cm⁻²) in the 3% TiN@TFP-BD composite compared to pristine TFP-BD. Additionally, thermoplasmonic heating in 3% TiN@TFP-BD (69.2 °C) surpasses that of TFP-BD (62.15 °C), accelerating mass transport during the photocatalytic process. This synergistic effect leads to a remarkable hydrogen evolution rate (HER) of 37.59 mmol g⁻¹ h⁻¹, an 8.5-fold improvement over the pristine COFs. Our work highlights the potential of thermoplasmonic enhancement for solar fuel production and establishes a new approach to mitigate excitonic limitations in COF-based photocatalysts.